Nonwoven products comprise loosely assembled webs or masses of fibers bound together with an adhesive binder. Adequately bonded nonwoven fabrics have advantages over woven fabrics for a large variety of uses. It is known to form bonded nonwoven fabrics by impregnating, printing or otherwise depositing an adhesive bonding composition on a base web of fibers. These fibers may be of cellulosic or polymeric materials such as wood pulp, polyesters, polyamides, polyacrylates and the like. The base web of nonwoven fibers, to which the binder is applied, can be produced by carding, garnetting, air laying, wet laying, paper making procedures, or other known operations.
The polymeric binder must imbue the bonded nonwoven product with acceptable dry and wet tensile strength and solvent resistance for the intended application.
One of the more successful copolymer binder compositions for nonwoven products comprises a vinyl acetate/ethylene/N-methylolacrylamide copolymer. (See U.S. Pat. No. 3,380,851).
U.S. Pat. No. 4,449,978 discloses nonwoven products bonded with a binder comprising an interpolymer of vinyl acetate/ethylene/N-methylolacrylamide/acrylamide. These nonwoven products have a low residual free formaldehyde content and good tensile properties.
U.S. Pat. No. 4,481,250 discloses an emulsion binder composition for nonwoven products having good wet tensile strength and low heat seal temperature which comprises an aqueous dispersion of a mixture consisting essentially of 50-95 wt% of a vinyl acetate/ethylene copolymer and 5-50 wt% of a vinyl acetate/ethylene/N-methylolacrylamide copolymer.
U.S. Pat. No. 3,081,197 discloses a nonwoven binder comprising interpolymers of vinyl acetate, another polymerizable compound as an internal plasticizer, and a post-curable comonomer such as N-methylolacrylamide.
U.S. Pat. No. 3,137,589 discloses binders comprising a copolymer of an alpha,beta-unsaturated carboxylic acid amide substituted on the nitrogen by at least one methylol group and another unsaturated polymerizable compound.